Autophagy is an evolutionarily conserved mechanism that plays important roles in both cell death and cell survival. ATG5 is an essential constituent for autophagosome formation, which sequesters cytoplasmic materials before lysosomal delivery. Although both cell death and survival are important in
cancer development, the role of autophagy in
prostate cancer development remains unclear. The aim of this study was to see whether alterations of
ATG5 protein expression and somatic mutations of the ATG5 gene are found in
prostate cancers. In the present study, we analyzed
ATG5 protein expression in 107 prostate
carcinomas by immunohistochemistry; additionally, we assayed the presence of ATG5 somatic mutations in 45 prostate
carcinomas by single-strand conformation polymorphism. Immunostaining of ATG5 in normal prostate cells was observed in 44.9% of the cases, whereas in prostate
intraepithelial neoplasm (PIN) and
prostate cancer cells, ATG5 was observed in 100% and 89.7% of the cases, respectively. Cytoplasmic expression of ATG5 that might be related to autophagy was seen in PIN (100%) and
cancers (83.2%), but not in normal cells (0%). ATG5 expression was not associated with any of the pathologic characteristics, including size of the
cancers, age, Gleason score, and stage. As for the ATG5 gene, we found no somatic mutations in the
prostate cancers. In this study, we analyzed ATG5 expression and mutation in
prostate cancers, and found that ATG5 expression was altered in
prostate cancers. The expression of ATG5, especially in the cytoplasm, in the
prostate cancers compared with normal prostate cells suggested that overexpression of this
protein may be related to autophagy and might play a role in prostate
tumorigenesis.